Hi All,

 

I'm hoping you can help me diagnose my 98' Legacy Outback 54K. I get a thump, thump, thump when accelerating from a dead stop. Happens more when I hit the gas hard from a stoplight. If I accelerate slowly, it won't make any noise at all. I replaced the passenger side axel which was suspect, but did not solve the problem. Thump seems to be coming from a little forward of the floorshift. Making me think it's the shaft. I've been under shaking things around, there is some play in there when I rotate the back tires, but not sure if it's too much or normal. Checked the heat shield and it's tight as can be. Any suggestions on how to diagnose?

 

thanks

get under the car and shake the driveshaft you have universal joints down there, plus a bearing and a bearing bushing.

 

 

nipper

get under the car and shake the driveshaft you have universal joints down there, plus a bearing and a bearing bushing.

 

 

nipper

 

should there be any play in the shaft? I have about 1 inch play in either direction.

I doubt it should be like that.

Have you had any work done to the transmission or the shaft recently? Check that the shaft sits in a straight line from the tranny to the rear diff. If the center berring is mounted in upside-down, it will cause the shaft to not be in a direct line, causing stress at the center berring, which will cause a thump thump effect when accelerating, turning, or under loads. This is just one more thing that could be a simpel fix to get your car back on the road.

should there be any play in the shaft? I have about 1 inch play in either direction.

 

thats a bad thing

 

nipper

1 inch is way too much if what yo'ure talking about and what i'm thinking about are the same thing. sounds like you need another driveshaft. VERY odd for them to fail that early.

Well I just finished pulling the shaft, not as much play as I originally thought. One thing that did catch my eye and I'm hoping someone can tell me if this is normal or not. The geared spling on the driveshaft which slides onto the transmission tail has a keyway, if you will at 12 and 6 o'clock. When I examined the trans tail it is geared all the way round, in other words no keyway. The reason I ask is that my car is a salvage project and I've found on more than one occasion where the wrong part was used as a quick fix. I also noticed some yellow numbers scribed onto the tube of the shaft much like one would see at a junkyard to identify parts. Makes me think this may not be the original shaft and a possibility it's the incorrect shaft.

 

Any suggestions/ideas would be great! Thanks

any play in the universal joints is too much. Is this an auto or manual

 

nipper

Sorry.. It's an automatic.

grr makes life hard.is ther any flex in the bearing moiunt or in the u joints, there should be none.

 

nipper

Not really.... they look 8 years old but can't say there is much if any play now that she's out of the car. I plan to take it to a driveshaft shop and have them asses it. Any comments on the gear differences I mentioned?

Not really.... they look 8 years old but can't say there is much if any play now that she's out of the car. I plan to take it to a driveshaft shop and have them asses it. Any comments on the gear differences I mentioned?

 

way cool your going to the best place you can go for this.

Well I just finished pulling the shaft, not as much play as I originally thought. One thing that did catch my eye and I'm hoping someone can tell me if this is normal or not. The geared spling on the driveshaft which slides onto the transmission tail has a keyway, if you will at 12 and 6 o'clock. When I examined the trans tail it is geared all the way round, in other words no keyway. The reason I ask is that my car is a salvage project and I've found on more than one occasion where the wrong part was used as a quick fix. I also noticed some yellow numbers scribed onto the tube of the shaft much like one would see at a junkyard to identify parts. Makes me think this may not be the original shaft and a possibility it's the incorrect shaft.

 

Any suggestions/ideas would be great! Thanks

 

im on drugs now so not sure what your asking. Can you show us a pic?

The shafts shouold be plined all the wasy aroound

 

 

 

nipper

There are no keyways in the Subaru driveshaft. if you have them, it may be that you do not have the correct shaft. You may want to go to a Pick and Pull and grab one from a similar car to yours

There are no keyways in the Subaru driveshaft. if you have them, it may be that you do not have the correct shaft. You may want to go to a Pick and Pull and grab one from a similar car to yours

 

that entire keyway thing wa throwing me off. Then the salvage car project, those can be a bit scary.

 

 

nipper

I'm not describing it accurately.. I'll try to post a pic of what I'm talking about.

The dude at the shaft shop said the 2nd piece was out 25 thousandths. He straightened it and no more vibration. We'll see when I put it back in the car.. I showed him the difference in splines and he told me it was normal, not to worry.

The dude at the shaft shop said the 2nd piece was out 25 thousandths. He straightened it and no more vibration. We'll see when I put it back in the car.. I showed him the difference in splines and he told me it was normal, not to worry.

 

 

that will do it every time. God i love driveshaft shops

 

nipper

palfer, all I can offer is my experience with my '96. The driveshaft spline is NOT keyed on mine. I don't know if any changes were made between '96 and '98, but I'd be somewhat suspicious of that drive shaft's heritage...

Well shaft is in... sad to say there is still a grumble/thump when I hit the gas from a stop. Not sure where to go from here.. maybe a junked shaft just for giggles.. thanks for the tips/suggestions everyone!!

I dont get a grumble, but a small thump when you step on it.

My sound comes from the front.

Prolly trans dropping into higher gear with a little more force via sudden higher rpms??